Re: [Qemu-devel] [PATCH 3/4] spapr: Code more defensively against lack of primary PCI bus

[Alexey Kardashevskiy <aik@ozlabs.ru>]

On 04/30/2013 07:45 PM, Alexander Graf wrote:
> 
> On 30.04.2013, at 06:33, Alexey Kardashevskiy wrote:
> 
>> Currently sPAPR always creates a primary PCI host bridge for emulated PCI
>> devices.  However, because the platform supports native virtual IO, and
>> can also support multiple independent PCI host bridges, it's quite often
>> useful to disable the primary bridge for debugging purposes.
>>
>> This patch, therefore, makes the code cope more gracefully with a missing
>> primary host bridge.
> 
> Does this handle the -net case too? What about disks?
> 
> If those use a different mechanism to find their bus, maybe it'd be better to instead do
> 
> if (phb) {
>     pcibus = phb->bus;
> } else {
>     pcibus = find_pci_bus();
> }
> 
> In fact, maybe the code already deals with bus==NULL?


I needed it to deal with phb==NULL.

The story behind this patch is that while doing VFIO stuff, I have to deal
with multiple PHBs. And sometime I want to be 100% sure that it is just
VFIO PHB and no emulated PCI stuff (especially when I debug USB PCI card in
VFIO) so I simply commented out the call which creates default emulated PHB
and that would be it if the existing code did not try to use phb->bus.




> 
> 
> Alex
> 
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
>> Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
>> ---
>> hw/ppc/spapr.c |    6 +++---
>> 1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c
>> index c96ac81..d07c74a 100644
>> --- a/hw/ppc/spapr.c
>> +++ b/hw/ppc/spapr.c
>> @@ -732,7 +732,7 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>     const char *boot_device = args->boot_device;
>>     PowerPCCPU *cpu;
>>     CPUPPCState *env;
>> -    PCIHostState *phb;
>> +    PCIHostState *phb = NULL;
>>     int i;
>>     MemoryRegion *sysmem = get_system_memory();
>>     MemoryRegion *ram = g_new(MemoryRegion, 1);
>> @@ -898,11 +898,11 @@ static void ppc_spapr_init(QEMUMachineInitArgs *args)
>>     }
>>
>>     /* Graphics */
>> -    if (spapr_vga_init(phb->bus)) {
>> +    if (phb && spapr_vga_init(phb->bus)) {
>>         spapr->has_graphics = true;
>>     }
>>
>> -    if (usb_enabled(spapr->has_graphics)) {
>> +    if (phb && usb_enabled(spapr->has_graphics)) {
>>         pci_create_simple(phb->bus, -1, "pci-ohci");
>>         if (spapr->has_graphics) {
>>             usbdevice_create("keyboard");
>> -- 
>> 1.7.10.4
>>
> 


-- 
Alexey